Just to add to the above post, while fresh tattoos are the most convenient to get pictures of from the artists, I have noticed that many tattooers take and post healed pictures whenever they can. I would imagine it can be difficult for top tier artists to get healed pic because of their scheduling and availability, wait times etc.
Personally all my work has come from the same artist and each time I go in, he always takes healed pics of the last piece. High demand artists don't always have that luxury.